For the record, Takaiwa-san is not full-on retiring yet. Apparently he'll still do suit acting, he just won't be in the suit for the "main" Rider. This move was bound to happen at some point (I still can't believe Takaiwa-san is actually 50 years old, AND he's still going). If anything, the fact that Japan is moving from Heisei to Reiwa makes this a logical/appropriate time for the changeover to happen.

I'm actually quite surprised (in a good way) that Kiriyama Renn (Hidari Shotaro in KR:W) ranked #1, especially given that (I believe) Sato Takeru (Nogami Ryotaro from KR:Den-O) has had a more prolific post-KR acting career. Maybe the women that they interviewed for this just have a preference for "half-boiled" types of guys.